I may be in over my head here but scouting through the source code in GitHub it seems like some of the Simple Gain sliders are duplicates? (Width, Gain and Delay are all called "Gain")
hi_core/hi_modules/effects/editors/GainEditor.cpp
//==============================================================================
GainEditor::GainEditor (ProcessorEditor *p)
: ProcessorEditorBody(p)
{
//[Constructor_pre] You can add your own custom stuff here..
//[/Constructor_pre]
addAndMakeVisible (widthSlider = new HiSlider ("Gain"));
widthSlider->setRange (-100, 36, 1);
widthSlider->setSliderStyle (Slider::RotaryHorizontalVerticalDrag);
widthSlider->setTextBoxStyle (Slider::TextBoxRight, false, 80, 20);
widthSlider->addListener (this);
addAndMakeVisible (gainSlider = new HiSlider ("Gain"));
gainSlider->setRange (-100, 36, 1);
gainSlider->setSliderStyle (Slider::RotaryHorizontalVerticalDrag);
gainSlider->setTextBoxStyle (Slider::TextBoxRight, false, 80, 20);
gainSlider->addListener (this);
addAndMakeVisible (delaySlider = new HiSlider ("Gain"));
delaySlider->setRange (-100, 36, 1);
delaySlider->setSliderStyle (Slider::RotaryHorizontalVerticalDrag);
delaySlider->setTextBoxStyle (Slider::TextBoxRight, false, 80, 20);
delaySlider->addListener (this);
addAndMakeVisible (balanceSlider = new HiSlider ("Balance"));
balanceSlider->setRange (-100, 36, 1);
balanceSlider->setSliderStyle (Slider::RotaryHorizontalVerticalDrag);
balanceSlider->setTextBoxStyle (Slider::TextBoxRight, false, 80, 20);
balanceSlider->addListener (this);
//[UserPreSize]
gainSlider->setup(getProcessor(), GainEffect::Gain, "Gain");
gainSlider->setMode(HiSlider::Decibel, -100.0, 36.0, 0.0);
gainSlider->setIsUsingModulatedRing(true);
delaySlider->setup(getProcessor(), GainEffect::Delay, "Delay");
delaySlider->setMode(HiSlider::Time, 0, 500, 100);
delaySlider->setIsUsingModulatedRing(true);
widthSlider->setup(getProcessor(), GainEffect::Width, "Width");
widthSlider->setMode(HiSlider::Discrete, 0.0, 200.0, 100.0);
widthSlider->setIsUsingModulatedRing(true);
balanceSlider->setup(getProcessor(), GainEffect::Balance, "Balance");
balanceSlider->setMode(HiSlider::Pan);
balanceSlider->setIsUsingModulatedRing(true);